Disclaimer: English Kinda Thing

The sole purpose of the "English Kinda Thing" is to document my attempts to correct my own mistakes in standard English usage and to share the resources I find. In no way do I attempt to teach nobody English through these blurbs--just as I intend not to teach nobody to be a neurotic and psychotic handicap in Ratology Reloaded or Down with Meds! :-)

Friday, July 10, 2009

Pain insensitivity in schizophrenia: Trait or state marker? (Singh, Giles, & Nasrallah, 2006)

Singh, M. K., Giles, L. L., & Nasrallah, H. A. (2006). Pain insensitivity in schizophrenia: Trait or state marker? : Journal of Psychiatric Practice Vol 12(2) Mar 2006, 90-102.

This study aims to provide a description for the phenomena of pain insensitivity in schizophrenic patients. It also tries to identify whether pain insensitivity is a trait or a state. In addition, the authors also attempts to propose a "multi-factorial model" based on the analyses of this article. The literature reviewed includes case reports, population-based studies and case series as well as empirical data.

Case reports

All of the patients mentioned in this class of articles did not report the perception of pain. Due to such distorted pain perceptions, their conditions were either misdiagnosed and treatments were delayed, which resulted in the worsening of the morbidity and mortality.

Population-based studies and case series

Prevalence of pain insensitivity in patients with schizophrenia

This type of studies provides a percentage value concerning the lack of pain complaints in conditions where pain should be present. Although many studies emphasized the lower

prevalence of pain complaints, studies have also shown that pain reports are not absent in schizophrenic patients (e.g., Ballenger et al, 1977, and Torrey, 1979). I can attest to this since I have had really bad pains that were incorporated into my delusional system (e.g., thinking I was being attacked by people remotely) when the conditions were so bad that I actually was institutionalized. An absence of pain and decreased pain reaction were also reported in young children who were institutionalized. This type of research could be used as evidence for the trait theory instead of state theory. At the same time, there also exists research that fails to report the decreased sensitivity towards pain in schizophrenic patients. Varsamis and Adamson (1976), for instance, had concluded that only the subgroup of patients marked to be withdrawal failed to report pain. One thing should be noted is that these studies did not utilize comparable pain assessments.

Prevalence of schizophrenia in people with pain

For people with chronic pain and referred to psychiatric treatment, the diagnosis of schizophrenia is far less prevalent than other diagnosis such as anxiety disorder and depression disorder. Some of the studies cited in the article actually found no patients with chronic pain with the comorbidity of schizophrenia. On the other hand, there are also studies finding no evidence of pain insensitivity in schizophrenic patients although more studies are needed to replicate these results.

Empirical data

Currently, there are two methods in this line of studies: psychophysical method and signal detection theory. The psychophysical method involves having subjects reporting the intensity and unpleasantness of the pain signal using words, numbers, line length or handgrip (Gracely, 1984). The major drawbacks of this method is the lack of reliability (Fernandez & Turk, 1992) especially in patients with limited verbal ability.

The second and more recent mode of investigation is the method of signal detection, which attempts to differentiate between the sensory (i.e., sensory discrimination) and affective (i.e., the report that the sensory experiences are painful) perspectives of pain. In this paradigm, patients with schizophrenia are first subjected to thermal, electrical, pinprick, cold pressor and pressured pain. Thereafter, their ability to discriminate the stimuli and their attitudes towards the perceptions of the stimuli are measured. This is considered as the accepted method in measuring pain in psychiatric patients because this is the only method separating the assessment of pain sensory and affect. Yet, this method also has its drawbacks. While what is assumed to measure sensory discrimination might actually be measuring non-sensory process, there is no telling whether the response criteria selected by the researchers really represent what is intended to be measured. Essentially, these are issues concerning the validity of the assessments.

Among the cited literature, following are some of the key findings that catch my eye:

  • One study found that schizophrenic patients' reaction to electrical stimuli were "ambivalent" and "dissociated"; such response pattern is similar to that of people with "brain lesion."—No wonder I feel brain dead most of the times. 8-O In addition, this reminds me of the time when I was receiving TENS (transcutaneous electrical nerve stimulation). It did not take me too much time before I hit the top intensity of the signal strength. Moreover, in my much younger years, I went for TENS kind of sessions for "weight loss" purposes. I also hit the top intensity in no time and it was even before the onset of my psychotic symptoms, which seems to speak for the trait theory concerning pain perception. The fact that I seemed to have higher tolerance or higher threshold towards electrical shocks before the onset of my psychosis seem to correspond with the line of research examining the pain sensitivity in health students with family psychiatric history.
  • Patients with paranoia were less sensitive to pain when comparing patients with other types of schizophrenia.—Since I am so very well endowed with paranoia (whether you believe it or not), am I not supposed to have less sensitivity to pain? In this case, how could I be with chronic pain? On a second thought, what is the possibility that I am actually enduring more pain than I know? 8-O
  • It is found that patients with chronic schizophrenia are less sensitive to electrical shocks and thermal pain when comparing to those with acute schizophrenia. Am I chronic or not?
  • Researchers have also tried to figure out the molecular basis for the presumed insensitivity to pain in schizophrenic patients. It has been suggested that there might be abnormal level of serotonin, dopamine, prostaglandins and endorphins in the brain for schizophrenics. Unfortunately, current literature yield conflicting results.
  • One study found that schizophrenic patients had worsening ability in sensory discrimination but did not differ from the control group in the response criteria required for the reports of pain. Higher response criteria were found to be more correlated with higher degree of flattening affect. The authors thus concluded that the observed insensitivity to pain might have more to do with affective abnormality.

It has been suggested, though, that earlier literature were loaded with methodological flaws including issues concerning sample size, diagnostic reliability and the use of control groups. Despite of the presumed methodological improvement in recent studies, there is still a lack of solid literature supporting the "hypoalgesia" in schizophrenic populations.

The author of this review then provided their thoughts about directions for future research etc.

The most important conclusion they had, at least for me, would be that… pain insensitivity seems to be a trait rather than a state. In addition, pain is a multi-dimensional phenomena or, in the authors' words, there need to be a multi-factorial integrated approach to pain perception.

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